• 한국농공학회논문집
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• 제54권1호
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• pp.93-97
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• 2012

Agricultural water reservoirs upstream of the intake on the basis of the intaking water volume is being made. Therefore, the supply capacity of reservoirs are not considered when the water balance analysis, storm water reservoirs are based on agriculture and further secured by the reservoir water is not used to using natural river water analysis. To overcome these problems can supply reservoirs are available to permit analysis of how much the quantity of water balance analysis, it should be reflected in the line to help. In this study, the natural daily flow data and apply the dimensions of the reservoir, and for more than 30 years of the long-term water balance analysis conducted by Date Youngsan river basin can supply reservoirs are large quantity of permits available is presented.

• 농업과학연구
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• 제40권3호
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• pp.243-252
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• 2013

This study was carried out to investigate safety evaluation of agricultural reservoirs due to raising the embankment. The seepage analysis and large-scale model test were performed to compare and analyze the pore water pressure(PWP), leakage quantity, settlement and piping phenomenon in the inclined core type and the vertical core type embankments. The PWP after raising the embankment showed smaller than before raising the embankment and the stability for piping after raising the embankment. The allowable seepage quantity and the allowable leakage for the steady state and transient conditions is within the range of safe management standard. After raising the embankment in the inclined core, there was no infiltration by leakage. For the vertical core, the PWP showed a large change by faster infiltration of pore water than in the inclined core. In a rapid drawdown, inclined core was remained stable but the vertical core showed a large change in PWP. Settlement after raising the embankment showed larger amounts of settlement than before raising the embankment. The leakage quantity before raising the embankment and the inclined core type showed no leakage. From the result, an instrument system that can accurately estimate a change of PWP shall be established for the rational maintenance and stabilization of raising the embankment for agricultural reservoirs.

• 한국농공학회논문집
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• 제63권4호
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• pp.97-104
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• 2021

Despite the practical limitations of calculating the amount of inflow and supply related to the operation of agricultural reservoirs, the role of agricultural reservoirs is gradually being emphasized. In particular, as interest in disaster safety has increased, the demand for preliminary measures to prepare for disasters has been rising, for instance, pre-discharging agricultural reservoirs for flood control. The aim of this study is to analyze the plans for the flood season reservoir operation considering pre-discharge period and water level limit. Accordingly, we optimized the simulation of daily storage using the ratio correction factor (RCFs) and analyzed the amount of inflow and supply using K-HAS. In addition we developed the drought determination coefficient (k) as a indicator of water availability and applied it for supplementing the risk level criteria in the Drought Crisis Response Manual. The results showed that it would be difficult to set the water level limit during the flood period in the situation of little water supply for flood control in agricultural reservoirs. Therefore, it is necessary to operate the reservoir management regulations after measures such as securing additional storage water are established in the future.

• 한국농공학회논문집
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• 제63권5호
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• pp.27-38
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• 2021

The physical condition assessment criteria of fill dam safety inspection are now weakly regulated and inappropriate for small agricultural reservoirs since these criteria have fundamental backgrounds suitable for large-scale dams. This study proposes the degree (critical values) of defects for the quantitative condition assessment of the embankment in order to prepare the condition assessment criteria for a small reservoir with a storage capacity of less than one (1) million cubic meters. The critical values of defects were calculated by applying the method that considers the size ratios based on the dimensional data of reservoirs, and the method of statistical analysis on the measured values of the defect degree which extracted from comprehensive annual reports on reservoir safety inspection. In comparison with the current criteria, the newly proposed critical values for each condition assessment item of the reservoir embankment are presented in paragraphs 4 and 6 of the conclusion. In addition, this study presents a method of displaying geometric figures to clarify the rating classification for condition assessment items with the two defect indicators.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.269-278
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• 1998

The Planning characteristics of the canals linking river basins and estuary reservoirs have been reviewed in relation to the trend widening the areas of water resources planning. It has been also tried to justify the characteristics of the link canals in the history of irrigation development. It was concluded that the link canals were resulted from the most recent technology as far as irrigation systems were concerned, why these were long- and large-scale multipurpose canals ； the hydraulic heads of the link canals could be controlled easily ； and which consisted of open channels, pipelines and control reservoirs. The types and general characteristics of the canals have been reviewed, and the fundamental concept and characteristics in the planning of the canals have been described.

• 한국농공학회논문집
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• 제56권1호
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• pp.71-79
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• 2014

In this study, an experiment with large-scale model was performed according to raising the embankment in order to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The pore water pressure, earth pressure, settlement and failure pattern by a rapid drawdown and overtopping were compared and analyzed. The pore water pressure and earth pressure at spillway transitional zone by overtopping increased a rapidly with the expansion of seepage erosion, but the crest showed a smally change due to effect of the inclined core type. And it is considered an useful data that can accurately estimate the possibility of failure of the reservoirs. A settlement at overtopping decreased a rapidly due to failure of crest. The relative settlement difference due to change of the water level at the upstream and downstream slope cause increase largely crack of crest. The behavior of failure by overtopping was gradually enlarged towards reservoirs crest from the bottom of the spillway transition zone, the inclined core after the raising the embankment was influenced significantly to prevent the seepage erosion.

• 한국농공학회논문집
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• 제49권3호
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• pp.3-10
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• 2007

In general method to estimate the water supplies in the large-scale basin, indirect estimation method such as unit loading factor method has been used. However, the estimated water supplies are much different to the real water supplies used in the any basin because these general methods estimate them considering water supply demands only. Especially, water supplies for irrigation are big different to the real water supplies in which the water supplies for irrigation are depend on the weather conditions such as evaporation, basin conditions such as infiltration, the reservoir operation rule for irrigation water, and distribution methods. Thus, a new estimation method is developed to estimate the real water demands which is essential factors for the effective water resources operation in the basin. This method is for estimating the water supplies and return rates based on the survey of the irrigation reservoirs and the analysis of effects to the stream flows, return flows, and water supplies for irrigation which water supplies and return rates are used in the basin water management model. The water supply usages in each subbasin are validated by comparisons between the simulated discharges from the basin water management model and the discharges measured in the control points.

• 한국농공학회지
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• 제24권1호
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• pp.44-52
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• 1982

Recently, estuary reserovoirs have been actively constructed in Korea and also in Japan there are a large number of estuary reservoirs constructed. But most of the estuary reservoirs are located at the downstream of a river where geographical condition is best for the construction of an enclosing dam. And an effective utilization of water from the estuary reservoir seems to be difficult even if estuary reservoirs are considered to be the water resources the most available for their watershed. Studies on estuary reservoirs so far have been mainly concentrated on the physical and engineering problems of the dam construction itself. The purpose of the present study is to review the estuary reservoir planning in connection with the water resources development and to study a basis of the planning. First, the levels of water use in Korea and Japan were compared with those of other countries in the world. And then, some representative reservoirs were selected to study the roles of a reservoir and water-using conditions in the watershed. Based on the study, a survey was given on the relation between a dam construction upstream and an estuary reservoir construction downstream of a river. Finally, a comprehensive examination was made of the bases of estuary reservoir planning. (1) The estuary reservoir planning is deeply related to the plan for water use develo- pment in the watershed. After the upstream water resources were fully developed up to the most, water reso- urces development by an estuary reservoir should be started. (2) If an estuary lake has a capacity big enough, it can store flood discharge of the watershed without any loss and become a basic facility that will bring about the maxi- mum use of water from the watershed. (3) Estuary reservoirs store water used in the upstream watershed, so recycling of water use is attained by the reservoir. Water in the estuary lake is difficult to be fresh water in its long run. Therefore, estuary reservoir should be located at a place where polluted water is purified and refused. All the planning should be based on the assumption that water in the estuary lake is not fresh but polluted after a long time. (4) The estuary lake can only supply water to the lower basin directly. But the upstream area is benefited from the estuary lake by exchange of irrigation water sources between the lower and the upper area. So a large-scale exchange plan between new and existing water resources is important. By constructing estuary reservoirs and the exchange of water sources between upper and lower areas, the reasonable maximum use of water from the whole watershed is at- tained. (5) The big problem coming from the water resources development by an enclosing estuary is salt water intrusion into the lake. To maintain the estuary lake salt-free, multi-purpose use of the lake should be avoided. It is necessary to take such fundamental measures as abolition of back flow operation of gate, and the closing of the fish port and the fish ladder. The results mentioned above were found in this study and these results of this study could be used for the adequate planning of estuary reservoirs in connection with the maximum water use of the watershed.

• 한국농공학회논문집
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• 제56권2호
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• pp.59-64
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• 2014

In this study, the large scale test was performed to investigate the behavior of failure for the embankment and spillway transitional zone by overtopping. The pore water pressure, earth pressure, settlement and failure pattern of covering embankment with geotextile were compared and analyzed. The pore water pressure showed a small change in the spillway transition zone and core, indicating that the geotextile efficiently reinforced the embankment. The earth pressure decreased the infiltration of the pore water only in inclined cores type to secure local stability. The behavior of failure started from the bottom and gradually progressed upwards. After the intermediate overtopping period (100 min), width and depth of the seepage erosion were very small due to the effect of geotextile which delayed failure. Therefore, the reinforced method by geotxtile was a very effective method to respond to the emergency due to overtopping.

• 한국농공학회논문집
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• 제54권5호
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• pp.141-153
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• 2012

In this study, we estimated probable precipitation amounts at the target year (2020, 2030, 2040) of 55 weather stations in Korea using the 24 hour annual maximum precipitation data from 1973 through 2009 which should be useful for management of agricultural reservoirs. Not only trend tests but also non-stationary tests were performed and non-stationary frequency analysis were conducted to all of 55 sites. Gumbel distribution was chosen and probability weighted moment method was used to estimate model parameters. The behavior of the mean of extreme precipitation data, scale parameter, and location parameter were analyzed. The probable precipitation amount at the target year was estimated by a non-stationary frequency analysis using the linear regression analysis for the mean of extreme precipitation data, scale parameter, and location parameter. Overall results demonstrated that the probable precipitation amounts using the non-stationary frequency analysis were overestimated. There were large increase of the probable precipitation amounts of middle part of Korea and decrease at several sites in Southern part. The non-stationary frequency analysis using a linear model should be applicable to relatively short projection periods.